Manual balancing valves or double regulating valves are primarily used in central air-conditioning plants to achieve balanced distribution of cooling/heating media, i.e. chilled/hot water. These are basically throttling valves installed at each Air Handling Unit, Fan Coil Units and at all branching points so as to bring the hydronic system as close as possible to the design condition at commissioning of the plant.
A conventional manual balancing valve is either configured in a globe valve pattern (as shown in FIG. 1) or in a Y-pattern and typically includes a hand wheel for manual fine flow regulation, a differential pressure measurement device to establish flow rate and a locking arrangement to prevent tampering of valve setting. Such valves also have an arrangement to memorize/store the valve setting so that the valve can be reset to previous set values. Also, the conventional valves provide tight shut-off. Moreover, these conventional valves have a calibrated proportionality factor “Kv” with guaranteed tolerance for each and every setting of the handle.
Manual balancing valves of up to 12 inches and having the afore-mentioned features are known in the art (as shown in FIG. 1). Large size balancing valves, i.e. above 12 inches, and having the typical configuration as shown in FIG. 1 are not available since the same are not manufactured due to huge size, weight and cost involvement. Such large size balancing solutions above 12 inches generally include a butterfly/gate/ball valve “B” being used as a throttling valve and a separate flow measuring device “F” coupled in series with the said valve, as shown in FIG. 2 that illustrates a schematic diagram of arrangement used for flow control for large size pipes. It is observed that such flow measuring device “F” would require a piping of minimum 7 times the nominal diameter of valve upstream of the flow measuring device and minimum 3.5 times the nominal diameter of the valve downstream of the flow measuring device “F” to get the desired accuracy in flow measurement. Consequently, a long piping is required to install such a large size balancing valve system to achieve balancing in air conditioning plants due to which plant design becomes difficult and it is not possible to achieve proper space utilization.
Thus, the conventionally known solutions for hydronic balancing in large piping (above the size of 12 inches) suffer from many inherent disadvantages, the primary one being the requirement to have approximately 10.5 times the nominal diameter of pipeline for installation, which is generally not available on plant sites. Also, in these conventional solutions, the throttling valve and flow measurement device are separate systems, as shown in FIG. 2 for instance. Moreover, the flow measuring primary element used in such balancing solution is either a fixed nozzle or includes flow nozzle with limited flow measurement range. Another drawback of such valves is that once the valves are shut-off, re-commissioning of the plant under balanced condition at a later stage requires flow measurement and adjustment to be carried out once again. In addition, the conventional systems are capable of working only when the flow is laminar. There are no available systems that effectively work with turbulent flow as well. Thus, it shall be apparent that the conventional balancing valves are not reliable and easy to operate and use of such balancing solution involves high cost in terms of material due to requirement of long length of piping and offer a limited flow range of operation.
Accordingly, there persists a need for a large sized balancing solution which is cost effective, simple in construction, reliable and easy to use.
Further, there persists a need for a large size balancing solution that incorporates all essential features required in balancing valves but at the same time has a short face to face distance.
Furthermore, there exists a need for a large sized balancing solution which does not require a separate flow measuring device or long length pipes for installation.
Moreover, there exists a need for a large sized balancing solution which can be used for controlling flow rate for a laminar as well as turbulent fluid flow.